Fossil Fuels My father rode a camel. I drive a car. My son rides in a jet airplane. His son will ride a camel. ~ A Saudi saying Facts do not cease to exist because they are ignored. ~ Aldous Huxley (1894-1963) CHAPTER 7 Fossil fuels are the most widely used form of energy in the world. They power practically every device we use and are used in every manufacturing application that we can imagine. Even the electricity generated to power a television or light a house is most likely produced using fossil fuels. The United States is the largest consumer of fossil fuels, which account for about 86% of its energy needs.1 Two-thirds of the electricity generated and almost all of the fuel used in transportation, comes from fossil fuels. Among the fossil fuels, oil and natural gas are the most popular because of their ease of transport, handling, use, and relatively low emissions. As these supplies are exhausted, they must be substituted by other forms of fossils, such as coal, oil shale, and tar sands. What is a Fossil Fuel? Fossil refers to the remains of animals, plants, or other life forms that have been protected from decomposition and oxidation for a very long time. Fuel refers to anything that can be burned as a source of energy. Therefore, fossil fuels are the remains of animals and plants that have formed into materials that can be burned. Since the source of these materials is living matter, they have the same composition as living organisms. They consist of fats, oils, paraffin (waxes), carbohydrates (sugars, starch, and cellulose), and proteins. Sulfur, phosphorous, and metals –although they can be burned—are not considered fossils because they do not originate from organic matter. Contrary to popular belief, fossil fuels are not the remains of dinosaurs; in fact, most fossil fuels were formed millions of years before the first dinosaurs lived. Since most lands were swamps, we can expect to find fossil fuels in areas that were once lush and housed many forms of plants and animals. The most likely sources are ancient trees, animals, fish, and tiny organisms that flourished in the oceans (Figure 7-1). Marshlands, subtropical and tropical swamps, lakes, lagoons, and river deltas are ideal sites. Figure 7-1 Fossil fuel 1 See Table 1-3, page 9. Carbon Cycle Since carbon is the major ingredient in fossil fuels, it is relevant to discuss the carbon balance in the atmosphere. Carbon exists primarily in the form of carbon dioxide, which is present in the air, dissolved in ocean water, or trapped in rocks and in plants through photosynthetic processes (See Chapter 7). Animals (including humans) consume plants as a source of nutrients and are part of the carbon cycle as well. Depending on the ultimate fate of dead animals and plants, carbon may return to the atmosphere as carbon dioxide or turn into fossil fuel. If the environment dries up, dead plants and animals will become exposed to air and react with it to produce carbon dioxide, thus completing the carbon cycle (Figure 7-2). However, if the environment is flooded with mud, stagnant water, silt, or sand, oxygen is cut off and the proteins and carbohydrates decompose from bacteria into a wax-like, organic, insoluble material called kerogen.2 The time it takes for kerogen to transform into fossil fuel ranges from tens to hundreds of millions of years, and depends on its depth in the ground, temperature, and pressure. Whether a fossil ultimately ends up as coal, oil, or gas depends on the original constituents of the kerogen and the conditions under which it is kept. If the origin of kerogen is from giant plants and stronger parts of plants such as lignin (material that strengthens the trunks and branches of trees), then carbon forms into very complicated structures and rings. These rings eventually connect together into a graphitic structure called coal. If the kerogen is formed from algae or plankton, they break into shorter chains that depending on their lengths, become a mixture of liquids (crude oil) and gases (natural gas). The deeper in the earth and more aged the kerogen, the greater the probability that the chains will break into lighter materials and a higher fraction of the kerogen will be in the form of natural gas. The carbon cycle is completed when fossil fuels are extracted and burned to form carbon dioxide and water. Combustion of Fossil Fuels Fossil fuel, whether in the form of coal, oil, or natural gas, reacts with oxygen in the air when burned, forming a number of products. In its simplest form, this chemical reaction can be written as: Fuel + Oxidizer Product Phot osy nt he s si Carbon Dioxide y ca De Fossil Fuels Carbon Cycle Dead Plants Dead Animals Plants Animals Figure 7-2 Carbon Cycle in the Atmosphere [adapted from Energy and Fuel in Society, by Radovic and Schobert, McGrawHill 1992]. This reaction always produces heat. Chemical reactions that produce heat are called exothermic reactions. In addition to carbon and hydrogen, fossil fuels may contain oxygen and traces of other elements, such as sulfur and metals, which complicate the combustion. In the present analysis, we assume that all impurities have been removed and the reactions are such that all the fuels are burned to produce carbon dioxide and water vapor. 2 K eros i s the Greek word for wax, and gen means more. 144 Chapter 7 - Fossil Fuels For example, methane, gasoline, and coal burn in oxygen as: Methane: Gasoline: Coal: CH4+ 2 O2 C8H18+ 12.5 O2 C+O2 CO2 CO2 + 2 H2O 8 CO2 + 9 H2O Such reactions, where the oxidizer is just enough to convert all fuels to carbon dioxide and water vapor, are called stoichiometric. When the reactant mixture has fuel or oxygen in excess of what is required for stoichiometric ratio, the mixture is fuel rich (oxygen lean) or oxygen rich (fuel lean), respectively. If air were used instead of oxygen, the reaction would remain the same except that the nitrogen in the air would appear unburned in the product. For example, the stoichiometric combustion of gasoline in air would be: C8H18+ 12.5 (O2 + 3.76 N2) 8 CO2 + 9 H2O +47.0 N2 (Air is a mixture of 1 part oxygen and 3.76 parts nitrogen). On the mass basis: 114 kg gasoline + 1,716 kg air or 1 kg gasoline + 15.1 kg air 352 kg carbon dioxide + 162 kg water vapor + 1,316 kg nitrogen 3.1 kg carbon dioxide + 1.42 kg water vapor + 11.54 kg nitrogen Question: As a result of fossil fuel consumption, roughly 6 billion tons of carbon is produced each year. It is estimated from geological evidence that each year about 30 million tons of carbon goes into the formation of new fossil sediments. What is the significance of this data in estimating the lifetime of remaining fossil fuels? Answer: The rate of consumption of fossil fuels is 200 times faster than the rate they are replenished by nature. This means fossil fuels are gradually being depleted and must be considered as a nonrenewable source of energy. Example: Calculate the stoichiometric air to fuel ratio necessary for burning the natural gas in air. Natural gas consists mainly of methane. Solution: The stoichiometric reaction of methane is CH4+ 2(O2+3.76 N2) 16 kg methane+ 275 kg air or 1 kg methane+ 17.2 kg air CO2 + 2H2O +7.52 N2 44 kg carbon dioxide + 36 kg water vapor + 211 kg nitrogen 2.75 kg carbon dioxide + 2.25 kg water vapor + 13.2 kg nitrogen Note that although methane and gasoline have very different structures, they have a similar air/fuel ratio and produce roughly the 145 same amount of carbon dioxide per mass of fuel burned. Incomplete Combustion If chemical reactions are completed fully, there would be little pollution and hydrocarbons would be a relatively clean source of fuel. Unfortunately, these reactions do not reach completion and other gases such as nitric oxides (NO and NO2) and carbon monoxide (CO) are always present. Because reactions take longer to reach completion than the time available in the combustion chamber, some hydrocarbons might also remain unburned in the product. Therefore, products will be exhausted before reaching equilibrium. The degree to which the reaction completes depends upon such variables as the combustion temperature and pressure, residence time, and mixture ratios. The details of the processes are outside the scope of this book and will not be discussed further. Those interested should consult more advanced texts on the subject.3 Heating Values Table 7-1. Heating Values for Common Fuels* Fuel Coal Kerosene Gasoline Methane Propane Coal Gas Methanol Garbage** Wood Hydrogen Calorific Value (kJ/kg) 15,000-30,000 43,000 44,000 55,600 50,500 34,000 19,800 19,800 20,000 143,000 Heating value (also called calorific value or heat of combustion) refers to the amount of thermal energy that is released by burning a unit amount of fuel.4 For gaseous and liquid fuels such as methane and gasoline, the heat of combustion is usually given per unit volume (37,000 kJ/m3 for methane and 39,000 kJ/lit for gasoline), while for solids such as coal, it is expressed per unit mass (15,000 to 30,000 kJ/kg).5 Roughly speaking, we can show the following relations between the energy releases of various forms of fossil fuels: 1 liter of petroleum ~ 1 kg of coal ~ 1 m3 of natural gas 1 gal of petroleum ~ 14 pounds of coal ~ 150 ft3 of natural gas It is interesting to note that, per unit mass, different fossil fuels have relatively similar calorific values (Table 7-1). This is logical due to the fact that all fossil fuels are hydrocarbons. Except for a slight variation in energy trapped between different bonds which form their molecules, these hydrocarbons are expected to release similar amounts of heat. For comparison, the heating values of hydrogen, firewood, and of garbage from a typical American household are also given. As we saw in Chapter 6, as much as 75% of the average American garbage content is paper, foodstuff, and yard waste; like fossil fuels, these derive their energy from living matter and thus can be burned in a manner similar to fossil fuels. Hydrogen is not a fossil fuel and does not contain carbon. Its high heating value is attributed to the much higher energy content trapped in H-H bonds relative to H-C bonds common in fossil fuels. * Calorific values are approximate and can vary somewhat depending on fuel purity. ** Garbage from a typical American household See for example, Seinfeld, J. H. Air Pollution: Physical and Chemical Fundamentals, McGraw-Hill, Inc., 1975. Heating values are expressed either as higher (gross) or lower (net) heating values, depending on whether the products of combustion are cooled back to their initial reactant temperature, and whether water in the combustion product is condensed out. If water in the exhaust is in the form of vapor, the heating value is called net or lower heating value (LHV). If the water vapor is cooled so all the water is condensed out, then additional heat is available and the heating value is called gross or higher heating value (HHV). For most reactions the exhaust is relatively hot therefore litt le condensation takes place and LHV is a more realistic number to use. The HHV is most appropriate in certain devices such as natural gas furnaces used in residential units and air conditioners that use condensers. 5 BTU equivalents of various energy sources are: 1 bbl crude oil = 5.8 million Btu; 1000 cu. ft gas = 1.03 million Btu; 1 kWh electricity = 3,400 Btu; 1 metric ton coal = ~30 million Btu. 4 3 146 Chapter 7 - Fossil Fuels US Fossil Fuels: The Facts Did You Know That ...? • • • • • • Over 95% of all US fossil fuels are still intact in the form of coal. The majority of petroleum in the United States is in four states: Texas, Alaska, California, and Louisiana. Contrary to popular belief, the major supplier of crude oil to the United States is not Saudi Arabia. It is Canada! Without oil imports, the United States has enough oil to last 10-12 years. After Saudi Arabia, the United States is the largest oil-producing country. US import of petroleum has increased from 8.4% of its consumption in 1950, to 30% in 1973, and to 55% today. The percentage of import is likely to increase to 70% by 2020. • Two-thirds of all US petroleum consumption is for transportation. Fossil Resources Major sources of fossil fuel are oil, coal, and natural gas. Tar sands and oil shale are also in large supply, but because of their high cost of production and their major adverse environmental impacts they have so far been largely ignored. As other resources deplete, these resources may prove to be a prominent source of fuel in the 21st century. Petroleum The term petroleum (nicknamed black gold) comes from the Latin roots petra, “rock,” and oleum, “oil”; it literally means rock oil and refers to gaseous, liquid, or solid hydrocarbons found beneath the earth’s surface in sedimentary rock formations. The two most common forms are natural gas and crude oil that, like coal, are formed from decaying animal and plant remains under very high pressures and temperatures underground. Unlike coal however, they can diffuse in porous sedimentary rocks and escape through the earth’s surface. Large reservoirs are formed only if the migration is stopped and oil and gas are trapped by the impermeable cap rocks. Since there is always some water and salt present, the oil is usually found above a pool of brine. Natural gas accumulates above the oil (See Figure 7-3). Petroleum is not only a convenient source of energy for generating electricity and powering our cars but also the main ingredient in much of the plastics, waxes, medicines, cosmetics, solvents, lubricants, feedstock, and a host of other petrochemical products used in our daily lives. In fact, because of its limited availability, many consider petroleum to be too valuable to be used in transportation, heating, and generating electricity. History of Oil Exploration in the United States OIL POOL CAP ROCK GAS OIL OIL BRINE BRINE IMPERVIOUS ROCK Figure 7-3 There is always some water and gas accompanying oil fields. Although oil has found its present place in the world for only the last century, it has been known to man as a useful product for a very long time. As early as 3000 B.C., oil was used by Mesopotamians (current Iraqis) as caulking to seal the cracks of buildings and joints in boats. The Egyptians used oil as a lubricant for their chariots, and the Romans used it to light their arrows before launching them at enemies. By 600 B.C., oil in Persia 147 was routinely extracted from oil wells that were only a few meters deep and brought to the surface by buckets and pulleys to be used in heating, lighting, and other purposes. In 1852, Abraham Gesner succeeded to distill kerosene from the crude which quickly replaced the whale oil which was more expensive, burned dirtier and was less luminous. The first commercial oil well in the United States was built by Edwin L. Drake in 1859 (Figure 7-4). It produced about 1000 gallons a day. Within one year, 2000 new oil wells were dug and a new industry was born. The oil boom in Pennsylvania did not last very long as wells dried up within a few years. Drake went bankrupt, dying a few years later. In 1864, a young entrepreneur, John David Rockefeller, purchased his first oil refinery in Cleveland, Ohio. As the Civil War ended and the country was fast becoming industrialized, Rockefeller saw the opportunity and bought additional refineries. To assure control over market and protect himself from wide fluctuations in the oil market, he moved and eventually acquired control over every stage of oil production from extraction to retail; this included transport, research, marketing, and even the manufacturing of barrels. In 1870, he combined his smaller companies into the Standard Oil Company and offered shares to the public. Being the largest customer of the railway industry, he managed to negotiate a favorable rate for transporting his crude, manipulated the price of kerosene, forcing many competitors to close their shops, file for bankruptcy, or sell assets to Rockefeller’s Company. By 1879, Rockefeller controlled 90% of all refinery operation and a quarter of all petroleum in the US. At the time that the average American worker was making $500 a year, Rockefeller’s wealth was estimated at several hundred millions.6 Threatened by his absolute control over the industry, several oil companies sued Rockefeller claiming the Federal Law prevents Rockefeller to operate any refineries other than in Ohio. Fearing loss of control, Rockefeller established the Standard Oil Trust. On November 1, 1879, Thomas Edison was awarded a patent for his most famous invention the “electric lamp.” The switch to electricity could adversely impact oil demand and price of the crude. The concerns did not last very long, however, when Henry Ford introduced his automobile (the horseless carriage), which was running on gasoline, a by-product of distillation of crude. Between 1900-1910, nearly half a million automobiles were sold, and with it petroleum found its prominent place in the American economy, and in doing so solidified Rockefeller’s power to control the price of oil. Figure 7-4 “Colonel” Edwin Drake. The first commercial oil well in Titusville, Pennsylvania. 6 L aughlin, R., John D. Rockefeller: Oil Baron and Philanthropist, Morgan Reynolds Publishing, Greensboro, North Carolina, 2004. 148 Chapter 7 - Fossil Fuels Algeria Iraq* Iran* Kuwait* Qatar Venezuela* Libya United Arab Saudi Emirates Arabia* Nigeria Indonesia *Founding Members Figure 7-5 OPEC member countries. Another threat soon was realized, when in 1901, the new oil discovery in Texas, attracted thousands of wildcatters and entrepreneurs.7 Wildcatters refer to persons drilling oil wells in areas not known to have oil in advance. Overnight, the US production of oil doubled and new powerful oil companies such as Gulf and Texaco were formed that challenged the Standard Oil monopolistic power that eventually led to a law suit by the government which accused Standard Oil of artificially manipulating prices. In 1911, the Supreme Court ordered the company to break into several smaller companies. Soon thereafter, World War I was in full swing, concluding only when the Allies successfully blockaded Germany’s oil supply routes and caused much of the German industry, trains, and military machines to come to a halt. WWI ended in 1918 only to reemerge 20 years later as WWII; again, conflict over the control of major oil fields in Poland and Russia played a large part in starting the war. With the discovery of huge reservoirs of oil in the Middle East in the years following WWII, there was a surplus of oil in the world market, and prices started to drop. To stabilize the sharply declining oil prices, as well as coordinate and unify petroleum policies, five countries (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela) established OPEC8 in 1960. Since then, seven other nations (Algeria, Angola, Libya, Nigeria, Qatar, the United Arab Emirates, and recently Ecuador) have joined the group (Figure 7-5).9 OPEC members collectively own 80% of the world’s proven oil reserves and produce 41% of the world’s oil, but consume only 8% of the oil (Figure 7-6).10 In contrast, the United States – with a little more than 2% of the reserves – uses more than a quarter of all oil produced in the world (Table 7-2). At present, US imports roughly 60% of its oil needs; as US resources deplete, this percentage is expected to rise (Figure 7-7). 7 8 Figure 7-6 World Petroleum Reserves, Production, and Consumption. Source: 2002 Transportation Energy Data Book, 2003. Table 7-2. Top Suppliers and Consumers of Petroleum* Who has it? Saudi Arabia Iran Iraq Kuwait UAE Venezuela Russia Libya Nigeria All Others 24% 12% 10% 9.1% 8.8% 7.2% 5.4% 3.5% 3.2% 17% Who uses it? US China Japan Russia Germany India Canada Brazil S. Korea All Others 25% 8.7% 6.1% 3.5% 3.2% 3.1% 2.7% 2.7% 2.6% 42% *Excluding canadian tar sands Source: Oil & Gas Journal, Vol. 103, No. 47,Dec. 2005. Oilen, R., and Hinton, D., Wilcatters: Texas Independent Oilmen, Texas A&M University Press, 2007. Organization of Petroleum Exporting Countries (htt p://www.opec.org). 9 I n May 2008, Indonesia announced that it has become a net importer of petroleum and therefore is pulling out of the OPEC. Ecuador rejoined the organization in 2007. 10 Transportation Energy Data Book, Edition 23, 2003. Table 1.5. 149 A Brief History of the Contemporary Middle East: Oil and Blood Digging Deeper ... He who owns the oil, will own the world... ~ Henri Berenger, French Oil Minister in 1919. E uropean interest in the Middle East dates back to the 16th century when the Portuguese Navy seized the island of Hormuz in the Persian Gulf to control trade routes to India, China, and the African coast. In 1798, Napoleon crossed the Mediterranean Sea and overtook Egypt. The opening of the Suez Canal in 1869 provided Europeans with a shorter shipping route that expanded their trades with India, China, and the Middle East, and with it the rivalry between two major European powers, France and Britain, for control of Egypt and later the rest of the Middle East. In 1872, Persia granted the British Baron Julius Reuter, the founder of the Reuters News Agency, a seventy-year contract to operate the railway and exploit its minerals including oil. This followed by a second major concession in 1901, to another British financier William Knox D’Arcy for exclusive right to explore oil and construct pipelines from anywhere in Persia to the Persian Gulf. In 1909, the Anglo-Persian Oil Company (later to be renamed the British Petroleum) was established to oversee the exploration and production. In 1908, major reservoirs of oil were discovered in Persia; shortly thereafter, the British fleet converted from coal to oil. By the start of the 20th century, the British and French had seized much of the Ottoman’s Arab territory, including Egypt, Sudan, Algeria, Morocco, and Tunisia. Kuwait, Qatar, Oman, and other Gulf states had become British protectorates. The Ottomans, however, had a firm grip on main Arabian (mainly Mesopotamia and Arabian Peninsula) oil fields. At the same time, internal combustion engines had been invented and oil had become a major source of contention in international affairs and as a major energy source driving the economy of the modern industrial world. When World War I began in 1914, the Ottoman Empire sided with the Austrians and Germans against the Allies, principally Britain and France. The Arab masses were left to decide between 500 years of Ottoman domination and the European conquest. As the Ottoman Empire weakened, the British sought the support of local Arab leaders, notably Hussein, the Sharif of Mecca, and his two sons Feisal and Abdullah (later to become rulers of Saudi Arabia, Iraq, and Jordan) who fought alongside the British against the Ottomans. WWI ended in 1918 only after Allied bombings of Romanian oil fields, which effectively cut much of the petroleum supply route to Germany.i Except for the Russian oil, three companies - Standard Oil, British Petroleum and Royal Dutch Shell controlled almost all the petroleum production in the world. After WWI, a bitter struggle for control of world oil reserves ensued. The British, French, and Dutch excluded US companies access to territories under their control. In 1920, Congress retaliated and passed the Mineral Leasing Act that punished those countries by denying them the right to produce oil in the United States. A settlement was eventually reached after all restrictions were removed by various parties to the conflict. Fearing that American oil reserves were being rapidly exhausted and to assure secure and continuous supply of oil for the foreseeable future, the US sought to establish ties with Middle Eastern oil exporters. In 1933, Standard Oil of California began exploration work in Saudi Arabia; it eventually merged with Esso (Exxon), Texaco, and Mobil and formed the California-Arabian Oil Company, later to be renamed the Arabian-American Oil Company (ARAMCO). 150 Chapter 7 - Fossil Fuels The Second World War (WWII) of 1939-1945 was the German attempt to reverse the defeat it suffered in WWI, and fulfill its imperial ambition over Europe, Russia, and the Middle East. Learning from its mistakes during WWI Germany had engaged in massive research and developmental work to extract synthetic oil from coal as well as stockpiling oil when needed.i To cut off the oil supply routes of the enemy, in 1941, Italian forces stationed in Libya invaded Egypt; Germans followed suit and attacked the Suez Canal. Both attempts failed, however. In May 1941, the British took control of Iraq; Iranian oil fields were seized later that year. As the war dragged on and supplies depleted, Germany launched its ill-fated attack against Russia, at least in part, for the capture of oil fields in Grozny, Baku, and Caucasus. As the Russian Army retreated, they destroyed all fuel supplies, denying Germans their much needed fuel. Germany was eventually defeated and WWII ended in 1945. Ironically, war ended once again when Allied forces destroyed, sabotaged, or blockaded the Romanian oil fields and refineries in Ploesti. In 1956, Egyptian president Gamal Nasser nationalized the Suez Canal. In 1958, a military coup overthrew the monarchy in Iraq. Ben Bella led Algerian independence in 1962; in 1979, the Iranian Revolution overthrew the monarchy. In September 1980, taking advantage of turmoil in the post-revolutionary Iran, Iraq invaded Iran, in part to seize control of the massive oil field on the Iran-Iraq border. The war lasted eight years and left over a million estimated dead. Having accumulated a debt of over $17 billion, Kuwait demanded unrestricted access to the Ramallah oil fields that laid 95% in Iraq. Taking advantage of the new and superior technology in slanted oil drilling allowed Kuwait to extract oil and sell it under OPEC official prices in the oil market. In an effort to keep Kuwait from what he claimed as Iraqi oil reserves, Hussein invaded Kuwait in 1990, which prompted US retaliation and the First and Second Gulf Wars in 1991 and 2003. At the time of this writing, another conflict is raised in the Middle East over the Iranian ambition to become a nuclear power and what many in the west see it as an attempt to build nuclear weapon. What is clear is that Middle East will continue to stay a hotbed of conflict and instability for many decades to come. Shwadran, B., The Middle East: Oil and the Great Powers, 3rd ed., New York, 1973. Becker, P. W., “The Role of Synthetic Fuel in WWII Germany: Implication for Today?,” Air & Space Power Journal, July-August 1981. ii i 151 With increasing dependence on foreign oil, developed countries will likely continue attempts to impose their will upon OPEC countries. Many of the oil producing countries (such as Iran and Venezuela) are, however, undergoing rapid economic expansion, and much of their oil production must be used to meet their domestic needs. This makes less oil available to export, with the result that oil revenues reduce for the exporter, and more expensive for the importer. This will necessarily put economic pressure on western and other developed countries, a prescription for regional and international conflicts and wars. The 1991 Gulf War and the 2003 US invasion of Iraq are just two examples of many future conflicts that are bound to occur over control of the vast Middle Eastern oil reserves11 (See box “A Brief History of the Middle East: Oil and Blood”). From Oil Well to the Gas Pump Finding Oil In the early days of oil exploration, few technologies could locate oil reservoirs precisely; they were mainly limited to random drilling of exploratory oil wells (wildcats). Today, advances in geological science and the availability of new sensors make this process considerably more accurate. Although no one technology can be used to accurately verify the presence of oil or pinpoint its exact location, combinations of various technologies improve the probability of success. Two technologies frequently used in geological mapping are the gravimetric and seismic methods. The gravimetric method uses variations in the local earth’s density as an indication of the presence of local deposits of coal, petroleum, or other ores. If earth were a sphere, uniform everywhere, the gravitational forces would be the same everywhere. The force of gravity is not uniform however, and changes somewhat with earth’s local density. On average, all objects are accelerated toward the center at the rate of g = 9.8 m/s2. Small variations of gravitational constant “g” can be accurately measured by a gravity meter and may indicate the presence of oil deposits. A gravity meter is essentially a mass-spring system in which the frequency of the oscillation is a measure of the gravitational constant. The seismic method exploits changes in the velocity of sound as it travels from one medium to another. Waves can propagate through a medium indefinitely until they encounter a boundary or discontinuity and are reflected back. In the seismic exploration technique, a shock wave initiated by a surface explosion propagates through the ground. When it detects a change in density (such as when it encounters an oil or a coal deposit), 11 A ccording to Hall, D. “Oil and National Security,” E nergy Policy, Vol 20, No 11, 1992), Iraq was a threat to US interests in two ways: First it could use its vast oil revenue to develop weapons of mass destruction WMD), and second, the combined reserves and production capacity of Iraq and Kuwait equaled those of Saudi Arabia which gave Saddam the ability to influence the internal policies of the United States. Figure 7-7 The US and the World petroleum. Note that US needs to import higher and higher percentage of its petroleum from foreign suppliers. 152 Chapter 7 - Fossil Fuels it reflects back. The reflected sound wave is measured by detectors (microphones) that are distributed at various locations around the detonation point. The time of arrival (velocity) and intensity (strength) of the reflected shocks, along with other data, are used to construct the 3-D geological map of the region and give information about the rock formation and potential presence of oil and coal deposits. Recent innovations in underground imaging and directional drilling allows development of 4-D geological maps (time is the fourth dimension) which track the motion of the fluid and increase oil discovery and recovery rates by 20%. In addition to gravitational and seismic methods, other techniques have been used to measure the electrical resistance and other properties of the surrounding rocks and porous media. Recovery Once geologists pinpoint the location of a potential oil reserve, drilling begins. With luck, the well will reach the oil directly. If not, it may have to be closed and another one drilled nearby. The earlier oil wells were easy to find and only a few meters of drilling were needed. Today, we might have to dig many thousands of meters to find any oil at all. Initially, oil is under sufficiently high pressure, which causes it to gush out naturally and no pumps are needed (flush production), but as more and more oil is extracted, a pumping facility can help maintain the flow of oil. The operation stops once the pressure has dropped below a point (the settled production point). This is the conventional method of production and is called the primary recovery method. About 30% of the oil can be extracted using the primary method. Beyond this point, additional oil can be recovered only by enhanced oil recovery techniques. Secondary recovery involves injecting water, natural gas, steam, or carbon dioxide into dead wells to raise the pressure or push the oil that is otherwise unavailable into neighboring wells (Figure 7-8a). An additional 10-15% of the available oil can be recovered using the secondary technique. Unfortunately it raises the cost of oil production by 50 to 100 percent. The tertiary recovery technique relies on reducing the oil viscosity. Viscosity is a measure of the ease with which a fluid flows (for example, water has a very low viscosity, but honey’s is high). Viscosity can be reduced by raising the temperature, either by injecting superheated steam or by combustion. In the latter, a small underground detonation results in a shock wave that propagates across the oil deposit. The shock wave heats the oil and breaks it into smaller molecules, making it flow more easily (Figure 7-8b). Another 10-15% of the oil can be recovered using the tertiary method. The combined primary, secondary, and tertiary methods can recover about 50-60% of the oil deposit. Once these techniques are (a) (b) Figure 7-8 Enhanced Oil Recovery: (a) Secondary - water flooding, and (b) tertiary - steam injection. Images Courtesy of Energy Information Agency, Office of Oil and Gas. 153 exhausted, the well is no longer usable and must be capped. Occasionally, oil wells are discovered below ocean surfaces and drilling must be carried out offshore. The process is similar to onshore drilling except that derricks must be mounted on platforms built away from shorelines. Platforms can be permanently built and fixed to the ocean floor or may float – anchored with wire rope and chains to the sea floor. Refining When extracted from the ground, crude oil is not pure, but contains sand, water, and a number of salts. Sand settles to the bottom of storage tanks and is easiest to remove. Other contaminants are removed by electric or chemical means. The crude is then sent into a distillation column where, depending on their boiling points, they separate into heating oil, kerosene, gasoline, and various gaseous fuels such as butane, propane, and methane (See Table 7-3). Table 7-3. Product of Petroleum Distillation Molecular Structure Gaseous fuels Ether Gasoline Kerosene Fuel oil Greases Paraffins (waxes) Asphalt and tar C1-C4 C5-C7 C5-C12 C12-C16 C15-C18 C18 and up C20 and up --Boiling Point (oC) -164 to 30 30 to 90 30 to 200 175 to 275 Up to 375 Semisolid Solid Residue in column Use Gas stoves, RVs Solvent Motor fuel Diesel and jet fuel Furnace Lubricant Candles Roofing and paving Finite or Not? Point/Counterpointpoint ... P: Newly adjusted OPEC data proves that reserves may not be finite but are continously expanding. CP: Much of the recent upward estimates of reserves are not warranted and were inflated by OPEC countries to increase their quotas. Furthermore, even with our advanced technologies, we have consistently found smaller deposits since the 1950s. In fact, today we are burning four barrels of oil for each barrel we discover. P: Technology makes finding other resources easier. CP: Newer technologies may increase the efficiency of oil recovery, which may extend the lifetime of petroleum a few years. It is doubtful however, that these technologies would meaningfully increase the total reserves. P: There are always other substitutes. CP: Other alternatives are of two kinds. Some, like solar and biomass, are more dispersed sources of energy and thus of lower quality. Others, like natural gas and coal, are themselves of limited supply and have niche applications. P: The primary and secondary methods of recovery being used today can only extract a little more than half of the oil before wells are recapped. We have a lot of oil still underground that remains to be tapped. CP: True, but there are available only if we are willing to pay much higher prices and if we find better methods of recovery. Then more oil resources are available and other resources such as tar sands and shale oils may become competitive. 154 Chapter 7 - Fossil Fuels Natural Resources: How Long Do They Last? One of the most intriguing questions of our time is the remaining quantity of our natural resources (fossils, minerals, precious metals, etc.) and the length of time they will last. Many have tried to answer this question, often with greatly different outcomes. Depending on the extent to which reliable data are available and the assumptions made, the answer often varies by degrees of magnitude. Accurate data are rarely available and at best, are only good estimates. Even so, it is often manipulated to suit the geopolitical and economical interest of a particular country, politician, or corporation. For example, consider the proven reserves of petroleum. OPEC uses data on available reserves to set quotas on the volume of oil each member can sell. To increase income, member countries tend to overestimate their reserves. On the other hand, oil companies are taxed based on their known reserves; therefore, to pay lower taxes, these companies tend to underestimate their reserves. Before delving further, we must distinguish between the reserves and resources that a certain region or country has. Resources are total quantities of a mineral in the crust of the earth -- the known and predicted deposits that may or may not eventually be sold for profit. The amount that has already been discovered or is believed to exist and can be exploited for profit (with today’s technology) is commonly known as the reserve. Resources continuously decline, whereas depending on its price and technology, reserves may or may not increase. Although we usually know the size of reserves to a good degree of certainty, we cannot accurately estimate what resources will be discovered in the future. The best we can do is to predict the probability of finding them. The uncertainty increases as we make our predictions farther into the future.12 W hether there is an upper boundary to a natural resource or not, that is, whether or not a resource is truly exhaustible, depends on whom we ask this question (see box “Finite or not?”). Optimists (also called cornucopians) argue that no natural resource is truly exhaustible. They point out that, as the reserves become scarcer, technological innovation will lead to the discovery of more alternative resources. In addition, production will become more efficient, which will reduce the cost and improve the reserves. Pessimists (some call them Cassandras or conservationists) argue that there will be a point at which all resources are depleted and the production process will eventually halt. While new technologies have enabled the discovery of new resources, the additional energy required may not justify further exploration. For example, we have to dig deeper and deeper to access oil as more and more is being extracted. That means the energy used per gallon of oil increases. Eventually we would reach a point where the cost of drilling and the energy needed 12 The v alues reported for oil reserves can vary widely from different sources. Companies and countries are deliberately vague about the likelihood of reserves they report. The values reported can vary from a low P-10 (10% probability) to a high P-90 (90% probability) chance of fi nding the resource. Exaggerated estimates by oil companies will raise the value of their stocks, but may also increase their share of taxes. OPEC countries may have an additional incentive to infl ate their estimates in order to boost their quotas for oil exports and obtain loans from international fi nancial institutions. The median estimate P-50, known as proven reserves, is probably the best estimate as errors and biases tend to cancel each other out. 155 to recover the oil would outpace the economic benefits (the break-even point) and explorations would necessarily stop. As a case in point, since 1980, oil demand has continuously increased beyond any new amounts of oil discovered.13 Uncertainty Reserves Resources Cost 1 2 B B' Depleted Remaining Reserves 1 2 A 0 0' A model proposed by the US Geological Survey, called “McKelvey’s Box,” is often used to address the relationship between reserves and resources (Figure 7-9).14 The size of this box represents the total amount of resources available. To the optimist, the box is not of a finite size, but varies with the cost of production and the probability that a resource can be found. If the resource is scarce, as the argument goes, its price continues to rise over time, the cost of production goes up, and there would be more effort in conservation and developing new technologies that can point to new discoveries and more efficient recovery methods. A A' Undiscovered Discovered A' Economical B B' Uneconomical Figure 7-9 McKelvey’s Box. The pessimists see the size of this box as finite, stressing that future discoveries and technological innovations cannot catch up with the demand, and that eventually the size of the reserves will shrink to zero. For example, data shows that US oil discoveries have decreased every decade since the 1950s (Figure 7-10) and that since 1962 (except in 1970 when Alaskan oil was discovered), the new oil reserves have never been enough to meet the rise in demand. Example 7-1: W hat is the upper limit to the quantity of oil that earth could contain? What is the exponential expiration time assuming that global oil consumption was 98.9 million barrels a day in 2000? Solution: The earth could not contain any more oil than the volume of the earth itself. Earth has an average diameter of 6,400 km, so its volume is Q = πd3/6 = 1.37x1011 km3 = 8.6x1020 barrels. If oil consumption continues to increase at a rate of 7% per year (T2 = 10 years), the time it takes the oil to be expired is given by Equation (4) in Appendix C. (C-4) EET = (1 /r ) ln(rQ / N + 1) 0 Figure 7-10 Oil discoveries by decade. Source: Campbell, C. J., and Laherrere, J., “The End of Cheap Oil?” Scientific American, V.278, No. 3, March 1998. Substituting for r = 0.07, N0= 98.9x106x365 = 3.61x1010 barrels/year, we get: EET = 1 0.07 ln (0.07. 8.6x1020 3.6x1010 + 1) = 303 Obviously the actual lifetime is much smaller than this as only a small fraction of the earth mass is composed of fossil fuels. Furthermore, this model assumes a constant rate of increase in oil consumption which is probably not a good assumption for many developing countries. No matter which point of view is considered, as time passes technological 13 14 L aherrere, J., “Forecast of Oil and Gas Supply to 2050.” Petrotech 2003, New Delhi, 2003. Online at: htt p://www.hubbertpeak.com/laherrere/Petrotech090103.pdf. It must be noted again that this model applies equally well to other “nonrenewable” natural resources, although for the sake of clarity, we are using oil as an example. 156 Chapter 7 - Fossil Fuels innovation and better production techniques allow a larger portion of resources to become economically extractable. Furthermore, as resources are depleted and prices rise, recovery of additional resources makes more economic sense and line BB shifts to B’B’ to the right. At the same time, expected discovery of more resources adds to the reserves and line AA moves down to A’A’ (Figure 7-9 bottom). As the total reserves (Figure 7-9 top left box) expand, so does the amount consumed, and the diagonal line 1-1 moves to 2-2. Putting it all together, we can see that the quantity of the remaining reserves can change as a result of two factors: 1. It increases due to discovery of additional resources, higher prices, newer technologies, and more efficient extraction and processing techniques. 2. It decreases because of additional consumption. The remaining reserve is the difference between the two. As long as this difference remains unchanged or increases in size, the resource is not depleting and is therefore sustainable. Unfortunately, for fossil fuels the trend is in the opposite direction, and the reserves continue to shrink. The most famous model pertaining to finite natural resources is that of geologist King Hubbert who, in 1965, predicted that US oil production would peak at about 1970 and decline thereafter (Figures 7-11). He also estimated that the world’s oil production would peak at around the year 2000. Furthermore, Hubbert predicted that 80% of the reserves would be depleted in about 60 years, and that even finding an additional 50% in new petroleum resources would not extend the petroleum life more than a few years. Although the predictions were made some 40 years ago, they seem remarkably accurate. For example, Hubbert’s predictions about US oil reserves, as well as those of the former Soviet Union and non-OPEC countries, have proven correct with only minor deviations. According to the latest worldwide estimates – even after including later discoveries of Alaskan, Siberian, Middle Eastern, and North Sea oils – the global production peak is expected to occur sometime around now (2007).15 Note that even if the future discoveries extend the proven reserves to twice the current estimates, the peak in oil production will only shift by a few years (Figure 7-12). Major OPEC countries have not reached their peak productions (mid-points) and cannot yet be tested against Hubbert’s hypothesis. Question: Hubbert based his model on the assumption that resources have a finite life and that production follows a bell-shaped curve symmetric about the peak, where half of all resources have been depleted.16 W hat was the basis of these assumptions? Answer: Hubbert made the assertion that oil discovery, like shooting 15 16 ∞ Figure 7-11 Hubbert’s prediction of the US oil reserves. The area under the curve is the total accumulative resource. Source: 1860 to 1965; M.K. Hubbert (Ref. 10); 1965 to present: BP, BP Statistical Review of World Energy (London: Pauffley Ltd, June 2004). 35 World oil production (Gbbl/yr) 30 25 20 15 10 5 0 1860 1880 1900 1920 1940 1960 1980 2000 2020 2040 2060 2080 2100 Q = 2000 Gbbl Q = 3000 Gbbl ∞ ∞ Year Figure 7-12 Effect of total reserve on lifetime. Source: Energy Information Administration, Internal petroleum Monthly, July 2006, Tables 4.1a-4.1e and 4.3. World Oil Production Estimates, Jean Laherrère at IIASA International Energy Workshop in Luxemburg, June 2001. Deffeyes, K. S., “The Hubbert’s Peak: The Impending World Oil Shortage,” Princeton University Press, 2001. 157 a target, is a statistical event.17 There is a certain chance that a sharp shooter will hit the bull’s eye, but there is also a chance he misses and lands some distance away. The probability drops as the shooter aims less and less accurately. Oil discovery is similar in the sense that the chance of drilling success is highly problematic. At the early stages, when a natural resource is discovered, the exploitation is slow and the chance of success in finding oil is small. Production is likely to rise exponentially as the most easily found reserves are exploited, technology becomes more mature, and additional uses for the resource are found. As reserves are used up and resources become scarcer, the probability of finding new resources declines; oil companies must dig deeper and production costs increase. Eventually, a point is reached where the rate of discovery reverses its course and starts to slow down. The rate continues to decrease until all resources are found and depleted. In Figure 7-13, the midpoints, when peak production occurs, are shown for various countries taking 2005 as a reference. As the data show, the United States, China, the former Soviet Union, and most other countries have already passed their midpoints. Only Saudi Arabia, Iraq, Kuwait, and the United Arab Emirates will be reaching their peak productions sometime within the next two decades. Table 7-4. Estimates of Proven Fossil Reserves, 2006 Oil (billion barrels) Figure 7-13 Production Midpoints (adjusted) for Major Oil Producing Countries from 2005. Natural Gas (trillion cubic meters) Coal (billion metric tons) US Middle East The World 30 785 1,371* 6 73 181 247 0.4 909 * Including Canadian tar sands Statistical Review of World Energy 2007, British petroleum (http://www.bp/com) Example 7-2: Assuming Hubbert’s predictions continue to hold true for the foreseeable future and that all the remaining reserves in the world are uniformly distributed between every man, woman and child, what is the length of time until all petroleum is consumed? Redo the problem assuming US reserves are divided equally among its citizens. Solution: According to the data in Table 7-4, the estimated total petroleum remaining (as of end of 2006) are 1371 and 30 billion barrels (Gbo) for the world and the US, respectively. During the same period, the world and the US’s annual consumptions are estimated at 83.7 and 20.6 million barrels a day. The population of the world was estimated at 6.5 billion and that of the US at 300 million.18 Therefore: 17 18 It is worth noting that the Hubbert model does not apply only to oil, but to other nonrenewable resources such as coal, natural gas, uranium, and minerals as well. US Census Bureau (htt p://www.census.gov/ipc/www/idb/worldpopinfo.html). 158 Chapter 7 - Fossil Fuels World: Per capita total share: Per capta consumption: Years remaining: 1371 x 109 = 163.8 barrels/person 6.5 x 109 83.7 x 106 x 365 = 5.73 barrels/person/year 6.3 x 109 211 = 28.6 years 4.7 US: Per capita total share: Per capita consumption: Years remaining: 30 x 109 = 100 barrels/person 300 x 106 20.6 x 106 x 365 = 25 barrels/person/year 300 x 106 100 = 4 years 25 There are, however, several flaws in this analysis. Among various important factors we can name: 1. The total estimate of reserves is probably based on faulty data, inflated by the oil exporting countries. For example, during 1988-1989, to increase their quota of oil imports (set by OPEC based on the total reserves of each member country), many Middle Eastern countries suddenly increased their estimated reserves by 246 billion barrels to a total of 660 billion barrels. 2. The rate of consumption is not going to remain constant and will most likely increase with time. The world consumption of energy is expected to continue to increase in the foreseeable future. This is a result of many factors; the population is expected to increase well into middle of the century, exports by OPEC countries will shrink, and as more migrants move to developed countries in search of better life and higher standard of living, they adopt the more energy intensive life styles.19 3. Not all the oil in the reserves will be pumped as quickly as the oil extracted today.20 Today, most easy-to-reach reserves have already been depleted; it is required to dig deeper into the ground, under ocean floors, and remote areas to access the remaining petroleum resources. On the other hand, there are undiscovered and inferred reserves that are not included in this analysis which could potentially extend the life of petroleum reserves for few additional years (See Table 7-5). The prospect is rather limited, however. Diamonds, J., Collapse: How Societies Choose to Fail or Succeed, Viking Penguin, 2005. A similar argument is proposed by C. J. Campbell in “The End of Cheap Oil,” Scientifi c American, March 1998. The reserves at the time were 1020 Gbo, and the annual production was 23.6, giving the world 43 years of supply. 20 19 159 Table 7-5. Total Petroleum Endowment: 2000 Assessment (billion barrels) World Cumulative Production Known Reserves Reserve Growth (Inferred Reserves) Undiscovered Resources Remaining Resources Total Endowment 708 883 682 1,290 2,855 3,563 US 169 24 70 183 277 446 Cumulative Production –The total amount produced as of 2000. Known (proven) Reserves – Identified reserves that have not been exploited yet. Undiscovered Resources – Resources postulated to exist from geologic information and theory outside of known fields. Reserve Growth –The increase in a known resource that can be inferred from the past historical data. Remaining Resources – Amount in discovered field that has not yet been produced. They are the sum of Known Reserves, Reserve Growth, and Undiscovered Resources. Total Endowment – Total resources that ever existed (cumulative production and remaining reserves). Source: USGS World Production Assessment 2000, http://energy.cr.usgs.gov. Coal Coal has been used longer than any other form of fossil fuel. Even early cavemen used coal (known as black rock) for heating purposes. In the United States and many other industrial countries, fuel wood was the dominant energy source until the sixteenth century. In the early seventeenth century, after many forests had been cleared and wood became scarce, coal substituted wood as the main source of fuel. The coal extracted from shallow streams was high in sulfur and burned with an irritating smell but also had some advantages. It burned at higher temperatures than wood and was more desirable for the smelting of irons and other metals. The coal byproduct, coke, was widely used in glass blowing, brick and tile manufacturing, and production of high purity metals that transformed the field of metallurgy.21 Another byproduct of coal, the coal gas, revolutionized the field of lighting, first on the streets of London and soon thereafter in other large European cities (See box “Coal Gas”). As more and more coal was extracted, the need for better drilling equipment, safety devices, and hauling carts increased. This led to important innovations ranging from reciprocating pumps to atmospheric engines and wagon tramways. In the early twentieth century, coal accounted for 90% of all energy supplies in the world, before it lost its dominance as an energy source to petroleum, a liquid fossil fuel that could easily be used in internal combustion engines. Today, coal accounts for a quarter of the world’s primary energy consumption, and generates 40% of all electricity. Similar figures for the US are 25% and 50%.22 21 22 Coke is produced by carbonization of coal in an oxygen-deficient environment and high temperatures. 2 004 estimates; a. World Coal Institute (htt p://www.worldcoal.org); b. US Geological Survey (htt p://energy.usgs.gov/coal.html). 160 Chapter 7 - Fossil Fuels Coal Gas FYI ... oal gas (also called town gas or synthetic gas) is produced by heating the coal or exposing it to hot steam in the absence of air to carbon monoxide and hydrogen. During the 19th century coal gas was used primarily in cooking and heating and later in the gas-lanterns used by most major cities. Because of its low caloric value and problems with tars, oil, and other pollutants, it was replaced by petroleum when the source was discovered. Coal gas can be burned directly or converted to methane, gasoline, or other petroleum products such as plastics and photographic film. C Types of Coal The quality of coal is typically categorized by its rank and grade. The rank of the coal represents its morphological development from peat to lignite (or brown coal), sub-bituminous, bituminous (soft coal), and anthracite (hard coal). The higher the coal is ranked, the greater is its carbon content, resulting in more energy being liberated when it is burned (Table 7-6). The grade of the coal determines its purity. Coal is of a better grade if its sulfur content is less and burns with lower emissions; coal is classified into low, medium, and high grades. Table 7-6. Coal Ranks and their Properties. Rank Anthracite Bituminous Sub-bituminous Lignite *Higher Heating Values. Age (million years) Carbon Content 85-95% 45-85% 35-45% 25-35% Heating Value (kJ/kg)* 350 300 100 60 34,000 and up 25,000-35,000 20,000-25,000 10,000-20,000 W hether coal ranks higher or lower depends largely on how it was formed. The first stage of coal formation involves the compression of vegetation under the heavy weights of water and ground materials. These materials gradually turn into a dark-brown, compact organic material known as peat. Over time, peat is compressed and heated to form lignite. Lignite is a soft, brownish-black coal, containing about 30% carbon. It is also the lowest quality and the most abundant type of coal in the world. Traces of the texture of the original wood may even be found in pieces of lignite. At greater depths, lignite is transformed into sub-bituminous, bituminous, and ultimately anthracite coal. Therefore, it is expected to find anthracite in the very old deposits that reside in the deep layers and to find lignite in the younger deposits and in those closer to the surface. Reserves and Resources Table 7-7. Major Recoverable Coal Resources Worldwide (2002 data)* Country Total Recoverable Reserves (Billion metric tons) Percentage of the total US Russia China India Australia Rest of the World Total 243 157 103 90 72 306 971 25.0 16.2 10.6 9.3 7.4 31.5 100 As Table 7-7 indicates, just five countries, the US, Russia, China, India, and Australia, own about 70% of the total world coal reserves – estimated at 976 billion metric tons. Despite what one might expect, with the exception of Iran, there are no coal mines in the Middle East. *EIA,2003 International Energy Annual Report, DOE/EIA-0219 (2003) 161 Large coal deposits are found in 38 US states, with more than half of these in only three states: Wyoming, West Virginia, and Kentucky. Anthracite is most commonly found in Pennsylvania and accounts for only 1% of the US’s coal reserves. About 70% of coal is bituminous; the rest is essentially lignite. Eastern and Mid-continent coalfields contain mostly bituminous coal, while sub-bituminous coal is predominantly found in the Western states. Most lignite is mined in Texas, Montana, and North Dakota. Worldwide coal production, which reached 4.8 billion metric tons in 2004, accounted for more than a quarter of all energy sources and about 90% of all electricity generated. In the United States, coal production grew exponentially from 1860 to 1910. As we switched our source of primary consumption to petroleum and natural gas, coal production (and consumption) leveled off until 1972, whereupon the rate started to rise again.23 The latest figures indicate coal consumption at one billion metric tons in 2004. The US’s proven, identified, and ultimate (identified and undiscovered) coal reserves are estimated at 247 billion, 1557 billion, and 3968 billion metric tons, respectively.24 The actual and projected US coal productions are shown in Figure 7-14. Although the US has the most coal reserves in the world, it is China that produces (and consumes) the most coal. The trend is expected to continue, and in the next two decades, coal use is projected to increase by another 36%, with the largest increases projected for China and India (Figure 7-15). In Europe, however, substantial declines in coal use are projected in favor of cleaner natural gas.25 Environmental Concerns Figure 7-14 US actual and projected coal production. Source: Historical data, EIA 2006. Figure 7-15 World coal consumption outlook by region (1990-2025). Source: Energy Information Agency, 2003. Air Pollution Impact HIGH Biomass Coal Petroleum Nuclear LOW Wind LOW HIGH Natural gas Coal is probably the dirtiest of all fossil resources; it produces more carbon per unit energy content, has the highest percentage of sulfur, and produces more nitric oxides. The relative impact on global warming and overall air quality is considered to be the greatest, producing twice carbon dioxide as oil for the same amount of energy (See Figure 7-16). Depending on how deep the coal is buried, coal can be extracted by digging tunnels or strip-mining. Hazards associated with tunnel operation include cave-ins, explosions from dust buildup, carbon monoxide poisoning, and lack of sufficient ventilation. Although tunneling operations harm miners the most, strip-mining has the greatest environmental impacts. These include the destruction of fertile surface-soil, permanent changes in the landscape, and the possibility of acidic or alkaline drainage to the surface (Figure 7-17). In many industrial countries, public and environmentalist pressure has forced local governments to require coal mining companies to reclaim the land and restore it to its original form after strip-mining. Greenhouse gas impact Figure 7-16 Impact of various energy technologies on global warming and overall air quality. 23 24 25 Barlett , A., “Fundamentals of the Energy Crisis,” Th e A merican Journal of Physics, 40, September 1978. pp. 876-888. E IA Website (htt p://www.eia.doe.gov/cneaf/coal/reserves/chapter1.html). E nery Information Agency Fact Sheet (htt p://www.eia.doe.gov). 162 Chapter 7 - Fossil Fuels Since coal is formed primarily underneath swamp beds, it contains a large amount of sulfur. To remove the sulfur, coal is crushed into small chunks and washed inside large water tanks. Since sulfur is heavier than coal, most sink to the bottom and is removed. Some of the sulfur is chemically bonded to carbon (organic sulfur) and cannot be washed off this way; it must be removed by adding chemicals that react with sulfur and break it loose. Although most sulfur is removed by physical and chemical processes, the coal burned in power plants still contains considerable amounts of sulfur which, when burned, produce sulfur dioxide. In addition to sulfur dioxide, nitrogen oxides and particulates are produced. Modern power plants use wet or dry scrubbers to remove the remaining sulfur in their smokestacks before it is released into the atmosphere. In wet scrubbers, limestone slurry is sprayed onto the flue gases where it combines with sulfur to form a paste that is left behind. Dry scrubbers consist of a fixed sorbent bed of activated carbon, char, and alumina impregnated with copper. Large bag houses remove larger particles while electrostatic precipitators filter smaller particulates. In addition to ecological concerns, coal extraction can be quite dangerous. It is estimated that several thousand miners are killed each year as a result of mine explosions, cave-ins, and carbon monoxide poisoning. As the energy crunch becomes tighter and the use of coal becomes more widespread, the number of mine accidents and fatalities are expected to increase. Of course, coal has a number of advantages. It is relatively cheap; it can be transported by truck, ship, and rail; it is easy to store and burn, and can be liquefied to produce synthetic oil. Every ton of coal will yield about 5.5 barrels of liquid fuel.26 It should be noted, however, that although there exists a large quantity of coal reserves to be exploited, if coal is used to substitute the current demand for petroleum, the coal supply would serve as only a very temporary solution to the problem.27 Oil Shale and Tar Sands Two potentially rich sources of fossil fuel are oil shale (or shale oil) and tar sands (or oil sands). Oil shale is actually a misnomer. It is not shale, but a rock, and it doesn’t contain oil, but rather a solid organic compound kerogen, which is tightly packed in clay, mud, and silt. Tar sands are grains of sand containing thick, viscous, soluble organic liquid called bitumen (Figure 7-18). The United States has two-thirds of the entire world’s oil shale (along shores of Green River in Wyoming, Colorado, and Utah), and Canada has the largest percentage of tar sands in the world (in Alberta). In fact, if tar sand reserves are included, Canada would have the second largest 26 27 Figure 7-17 Shale oil can potentially meet a great portion of the future energy demand. Lumpkin, R.E., “Recent Progress in the Direct Liquefaction of Coal,” Science , 239, p. 873, 1988. Hatfield, C. B., “How long oil supply grow?” M. King Hubbet Center for Petroleum Supply Studies, Newsletter #97/4-1-6, October 1997. 163 amount of petroleum reserves in the world after Saudi Arabia.28 Russia and Brazil are also rich in oil shale, whereas Venezuela has the second largest deposits of tar sands (after Canada). Worldwide resources of tar sands are estimated at around two trillion barrels.29 An additional 2.8-3.3 trillion barrels of oil can be recovered from oil shale.30 Mining operations are very energy intensive; oil shale resides deeply underground and must be heated to high temperatures (around 400-500oC) before it releases any oil. In fact, the oil extract is not petroleum, but liquid kerogen. Steam is needed to hydrogenate kerogen into hydrocarbons that may then be refined into gasoline and other petroleum products. Tar sands must also undergo a similar process. Heating them to high temperatures causes the viscosity of the bitumen to drop, making it flow more easily out of the sand. Various petroleum products, such as kerosene can be manufactured by distilling the kerogen and bitumen oils. Figure 7-18 The huge equipment used in strip-mining operations illustrates the dramatic impact that mining has on neighboring communities. In addition to their low yield (50-100 liters per ton of rock), oil shale and tar sands are not clean. These resources are rich in sulfur and nitrogen which can contribute significantly to the acid rain problem. Another environmental concern is the disposal of residues, called tailing, which occupy many times the volume of crude they produce. These problems have hindered widespread use of oil shale and tar sands. Canada is pursuing mining tar sand deposits aggressively; Estonia, Brazil, and China use oil shale to produce electricity and in production of cements. As the price of petroleum rise, these resources will find a more prominent role to meet our energy needs. Natural Gas The same factors that promote the formation of petroleum also help in the formation of natural gas. It is therefore expected that natural gas is found at locations near oil fields, often in association with petroleum (thus its name associated or dissolved gas). It is liberated when oil is brought to the surface in the same manner that carbon dioxide gas is liberated when someone opens a carbonated drink. If the gas diffuses through the pores of sedimentary rocks and accumulates in a reservoir other than the oil reservoir, the gas is called non-associated gas. Up to only a few decades ago, most natural gas discovered was flared off or reinjected into the ground, as it was considered to be of little use. Its use increased during the latter half of the twentieth century, as it proved to be a convenient and relatively clean fuel to be burned in gaseous burners for space heating and cooking (Figure 7-19). Natural gas is primarily methane (CH4), but a certain percentage of heavier hydrocarbons such as ethane (C2H6), propane (C3H8), butane (C4H10), and a small amount of pentane (C5H12) and hexane (C6H14) are Figure 7-19 Natural gas, the cleanest of all fossil fuels. 28 29 George, R L, “Mining for Oil,” Scientifi c American , March 1998. D uncan, D. C., and Swanson, V. E., “Organic-rich shale of the United States and world land areas,” US Geological Survey Circular 523, 1965. 30 “ Annual Energy Outlook 2006,” E nergy Information Energy, February 2006. 164 Chapter 7 - Fossil Fuels also present. At normal temperature and pressure, pentane and hexane are liquid, but in elevated temperatures and pressures underground, they become gas and flow out with other gases. Commercial natural gas is primarily a mixture of methane and ethane. The propane and butane are liquefied and sold separately as liquefied petroleum gas (LPG) or “bottled” gas. For a long time, many producer countries used to burn natural gas at the well. This was very wasteful and caused huge environmental problems. Because of its lower density, it costs about four times as much to transport natural gas through pipelines as it does for crude oil; these gases are liquefied and shipped to their destinations as liquefied natural gas (LNG) in huge cryogenic containers aboard large tankers and ocean liners. Reserves, and Resources Table 7-8. Total Natural Gas Endowment (bbo equivalent)* World Cumulative production Undiscovered reserves Reserve growth (inferred) Remaining (proven)reserves Total Endowment 292 866 610 799 2567 US 142 88 59 29 318 * For definitions refer to Table 7-5. Source: USGS World Production Assessment 2000 ( http://energy.cr.usgs.gov) Table 7-9. World Proven Natural Gas Reserves as of Jan. 1, 2006 Country Total Recoverable Reserves (trillion cubic feet) The total amount of available natural gas is shown in Table 7-8. Roughly two-third of all natural gas reserves lie in Russia and the Middle East (Table 7-9). The United States with 193 trillion cubic feet has a little more than 3% of the world’s natural gas reserves.31 Because natural gas is relatively clean, its rate of consumption is increasing by an average of 2.8% annually, faster than other sources of fossil fuels (Figure 7-20). If consumption continues to grow at this rate, natural gas reserves remain available for another 75 years. However, this number is believed to be optimistic, as natural gas substitutes coal and petroleum in an effort to reduce the effect of greenhouse gases.32 Besides wells, however, there are other sources of natural gas such as hydrates that if they could be extracted, would provide energy for many hundreds of years. Hydrates are icy deposits of crystallized natural gas and water, buried under the extreme pressures and cold temperatures of the deep oceans and Arctic permafrost that have been formed by the disintegration of certain bacteria. It is estimated that gigantic hydrate fields around the world contain twice the energy of all other forms of fossil fuels combined. These reserves are virtually untapped, as there are major obstacles that have to be overcome before the reserves can be accessed. Any major changes in temperature or pressure may be capable of breaking down the material, releasing huge amounts of methane – a very potent greenhouse gas (See box “The Deadly Lake”).33 The cost of extraction is prohibitively high and the natural gas, even if it is extracted, has to be transported thousands of miles from Arctic regions before it can be used. One solution is to convert it to liquid synthetic fuel, such as methanol, before it is sent through pipelines. Percentage of the Total Russia Iran Qatar Saudi Arabia UAE Other Mid.East US Rest of the World Total 1680 971 911 241 214 223 193 1,679 6112 30.5 15.9 14.9 3.9 3.5 4.1 3.1 24.1 100 Source: Energy Information Agency, 2006. Figure 7-20 The outlook for worldwide natural gas consumption Source: Energy Information Agency, 2005. E nergy Information Agency Fact Sheet, htt p://www.eia.doe.gov. Meadows, D., Limits to Growth: 30-Year Update, Chelsea Green Publishing Company, 2002, p. 94. A few petroleum geologists have gone so far as to blame the loss of ships and airplanes in the Bermuda Triangle on sudden pulses of methane gas released from a hydrate layer below the Atlantic Ocean. As the ocean boils with a sudden squirt of methane bubbles, ships can be swallowed before having time to make distress calls, and plane engines might be choked by the rising plume of methane gas. 32 33 31 165 The Deadly Lake FYI ... L ake Kivu on the border between Congo and Rwanda is unique in the world in one important way: it conceals an enormous quantity of water -- 65 billion cubic meters -- lying dormant at the bottom of the cold lake.i Furthermore, the lake is continually being recharged with the gas, giving Rwanda an almost inexhaustible source of relatively clean energy. The source of this gas is believed to be tiny single-celled microorganisms called archaea that consume dissolved carbon dioxide from two nearby active volcanoes to produce methane. Some methane is also formed through bacterial fermentation of acetate in the lake bed sediments. Deeper waters can trap methane to higher concentrations. If water is brought to the surface, either by a pump or naturally through mixing or siphoning, it will lose its ability to hold the methane, releasing it in form of gas bubbles that can be collected and piped away. Methane, being 25 times less soluble in water than carbon dioxide, is bubbled first leaving carbon dioxide dissolved in the water. If water is saturated and the buildup of methane gas is allowed, it can form an explosive danger with catastrophic consequences. A fiery disaster or be a blessing in disguise for the 2 million people who live along the shore ii i Halbwachs, M., et al. “Investigation in Lake Kivu after the Nyiragongo Eruption of January 2002,” European Community Humanitarian Office, Communauté européenne – ECHO 1 rue de Genève B- 1049 Bruxelles. iI Bavier, J., “Deadly Mix of Gases Lurks in Congo’s Lake Kivu; Explosive Methane Could Be Tapped To Generate Power,” The Washington Post, June 17, 2007. Converting natural gas to liquid first requires breaking its chemical bonds using steam, heat and a nickel-based catalyst to produce a mixture of carbon monoxide and hydrogen known as syngas. This process is called steam reforming. Syngas is then blown over various catalysts to transform it into gasoline, diesel, and other liquid hydrocarbons. Summary No doubt fossil fuels have been and will remain as the most important source of energy. Much of today’s technology has come about because of the availability of cheap and abundant fossil reserves. Unfortunately, in a relatively short time, we have managed to consume nearly half of our estimated conventional oil and much of our coal and natural gas resources. It is particularly noteworthy that by 1970, over half of the globe -- Africa, ME, Asia (except Japan)-- did not essentially use any oil. This is becoming particularly difficult as the demand for oil is increasing in much of the world. Developed countries, at least in foreseeable times, will consume more. As developing nations strive for better economic conditions, they will demand more share of the energy resources. Similarly, as Middle Eastern countries become industrialized, they will use more of their resources locally, leaving less available for export. Furthermore, with a majority of OPEC members in the Middle East, the political instability in this region can easily disrupt the flow of oil, increasing global conflicts and the potential for even more military interventions and war. This will have a spiraling effects of higher prices of petroleum, economic downturn, and even more conflicts. Unless we make drastic adjustments in our patterns of use, we may not be able to enjoy these resources for much longer. Fortunately, there is hope that new sources of energy will become available at reasonable prices. Nuclear energy can offset rising demand for a short period. Tar sands and oil shale can extend the life of petroleum for some 166 Chapter 7 - Fossil Fuels time. Similarly, methane hydrate is a huge potential source of natural gas. Alternative and clean sources of energy are also being developed at prices that are continuously being lowered. Until then, all we can do is to use the available reserves sparingly. Additional Information Books 1. Berkowitz, N., Fossil Hydrocarbons: Chemistry and Technology, Elsevier Academic Press, 1997. 2. Deffeyes, K. S., Hubbert’s Peak: The Impending World Oil Shortage, Princeton University Press, Princeton, N. J., 2001. 3. Campbell, C. J., The Coming Oil Crisis, Multi-Science Publishing Company, 2004. 4. Tariq Ali, The Clash of Fundamentalisms: Crusades, Jihads and Modernity, Verso, 2002. 5. Pelletiere, S., Iraq and the International Oil System: Why America Went to War in the Gulf, Praeger Publishing, 2001. Periodicals 1. Oil and Gas Journal, Technology, news, statistics, special reports, and analysis (http://ogj.pennnet.com). 2. Journal of Petroleum Technology, The official journal of Society of Petroleum Engineers, Dallas. 3. The Petroleum Engineer, Petroleum Engineer Pub. Co. 4. Journal of Petroleum Science and Engineering, Elsevier, covers the fields of petroleum (and natural gas) exploration, production and flow. Government Agencies and Websites 1. National Energy Technology Laboratory: The Strategic Center for Coal (http://www.netl.doe.gov/coal). 2. National Petroleum Technology Office (http://www.npto.doe.gov). 3. US Geological Survey (http://www.usgs.gov). Non-Government Organizations and Websites 1. Organization of Petroleum Exporting Countries (OPEC) (http:// www.opec.org). 2. Society of Petroleum Engineers (http://sae.org). 167 Exercises I. Essay Questions 1. Who are the top five producers and top five consumers of petroleum? 2. When was OPEC established and why? Name eight of OPEC’s member states. 3. How much carbon dioxide is put into the air for every gallon of gasoline burned in an average car? 4. Where are the main sources of tar sands and shale oil? What are major impediments in using these resources on a large commercial scale? 5. How is coal classified? What are the characteristics of the best kind of coal? 6. What are the underlying assumptions in Hubbert’s model? According to his model, when will half of all total reserves (past and future) be used up? 7. What is the difference between reserves and resources? In your opinion, is there a limit to the amount of reserves in the world? 8. What are some of the techniques for discovering oil? Explain the principle of operation for two of them. 9. What are the advantages and disadvantages associated with tar sands and oil shale? What is the role that these resources will play in meeting the future energy needs? 10. Explain the sources of conflict in the Middle East. How are they related to oil? Is there a sensible solution to problems gripping this region? II. Multiple Choice Questions 1. Which energy source is used most by the United States? a. Coal b. Petroleum c. Natural Gas d. Solar 168 e. Hydroelectric 2. After Saudi Arabia, the US a. Has the largest oil reserve b. Has the largest oil resources c. Is the largest oil producer d. Has the largest coal deposits e. All of the above 3. Gasoline is a product of refining a. Coal b. Petroleum crude c. Natural gas d. Propane e. Ethanol 4. What percentage of the world’s proven oil reserves is in the United States? a. 2-3% b. 10-12% c. 15-20% d. 25-30% e. More than 30% 5. Natural gas is transported mainly by a. Pipelines b. Trucks c. Barges d. Trains e. All four, roughly equally 6. The three countries with the largest petroleum reserves in the world are a. Saudi Arabia, United States, and Russia b. Saudi Arabia, Venezuela, and the United Arab Emirate c. Saudi Arabia, Iran, and Iraq d. Iran, Iraq, and Kuwait e. United States, China, and Russia 7. The top three oil consuming countries in the world are a. Saudi Arabia, United States, and Russia b. United States, India, and China c. Saudi Arabia, Iraq, and Kuwait d. United States, China, and Russia e. United States, Japan, and China Chapter 7 - Fossil Fuels 8. Among the OPEC members that border the Persian Gulf are a. Iran, Libya, Kuwait, and Saudi Arabia b. Iran, Iraq, Algeria, and United Arab Emirates c. Iran, Iraq, Kuwait, and Saudi Arabia d. Iraq, Venezuela, Qatar, and Saudi Arabia e. Pakistan, Iran, Iraq, and Kuwait 9. The largest reserves of natural gas are in a. Saudi Arabia b. Iraq c. The United States d. The Russian Federation e. China 10. The largest reserves of coal are in a. Saudi Arabia b. Iraq c. The United States d. The Russian Federation e. China 11. Petroleum is primarily used in the United States in a. Transportation b. Generating electricity c. Heating and cooling buildings d. The petrochemical industry e. The pharmaceutical industry 12. In pockets containing petroleum, a. Oil is on top, water in the middle, and gas at the bottom b. Oil is on top, gas in the middle, and water at the bottom c. Water is on top, oil in the middle, and gas at the bottom d. Gas is on top, water in the middle, and oil at the bottom e. Gas is on top, oil in the middle, and water at the bottom 13. Most of the United States’ oil imports are from a. Canada b. Mexico c. Saudi Arabia d. Alaska e. Europe 14. Over ______ percent of all petroleum reserves lie in the Persian Gulf region. a. 99 b. 90 c. 80 d. 60 e. 20 15. Natural gas combined-cycle combustion turbines a. Have greater combined efficiency b. Have lower rates of pollutant emissions c. Can be used as central or distributed d. Reject heat at lower temperatures e. All of the above 16. Propane is the fuel of choice on farms and in rural areas, mainly because it is a. Safer b. Portable c. Cleaner d. Cheaper e. More plentiful 17. Which country is the largest coal producer in the world? a. The United States b. Russia c. China d. India e. Germany 18. Which of the following statements is correct? a. Natural gas is formed by heating petroleum until it is turned to a gas. b. The largest reserves of natural gas are in Russia and Iran. c. Natural gas reserves can be found only where there is oil. d. After the Middle East, The United States is the largest producer of natural gas. e. Natural gas is composed of methane, ethane, and propane in roughly equal proportions. 19. Which US state is the largest producer of petroleum? a. California b. Louisiana 169 c. Alaska d. Texas e. Pennsylvania 20. Which fossil fuel creates the lowest amount of carbon dioxide per kilogram of fuel burned? a. Methane b. Methanol c. Coal d. Petroleum e. All four produce about the same amount 21. For each kilogram of gasoline we burn in our cars, we pollute about ______ kilogram of air. a. 1 b. 15 c. 100 d. Over 1,000 e. Cannot tell 22. The amount of a natural resource that may become available for use is called a. Reserves b. Reservoirs c. Resources d. Supplies e. Capacity 23. Proven reserve refers to a ________ percent probability of finding new reserves. a. 10% b. 50% c. 90% d. 99% e. 100% 24. Peat a. is the highest quality form of fossil fuel b. is the first stage in the formation of coal c. is embedded in tar sands d. is made by compressing animal dung e. is the nickname for Peter 25. Which of the following statements is true about tar sand? a. Tar sand is expected to play a significant role in energy production in the 21st century. 170 b. About 2/3 of all tar sand deposits in the world resides in the US. c. Tar sand is a clean source of energy. Unfortunately it is expensive to produce. d. Per mass basis, tar sand yields a relatively large amount of energy. e. All of the above. III. True or False? 1. Coal, petroleum, natural gas, and propane are called fossil fuels because they are formed from the buried remains of plants and animals that lived millions of years ago. 2. It is possible to find natural gas even if no petroleum is found. 3. It is estimated that over 70% of all of the world’s recoverable natural gas has been used already. 4. Hydrogen is the cleanest form of fossil fuel. 5. Chemical reactions that release heat are called exothermic. 6. The secondary recovery technique relies on reducing the oil viscosity. 7. At the point at which oil production reaches its peak, half of all oil has been already consumed. 8. Peak production represents the mid-time that a particular resource is available to us. 9. The P-90 reserve figures generally over- estimates the amount of proven reserves. 10. With the existing technologies, over 90% of all petroleum reserves can be extracted. 11. During the next doubling time for coal production, we will use as much coal as we have used up to this point. 12. According to many experts, global oil production will peak sometime during this decade. Chapter 7 - Fossil Fuels 13. A great portion of coal reserves resides in the Middle East. 14. At the current rate of consumption, the remaining US coal resources should last an additional 300 years. 15. Oil shale is an oily substance found usually in seashells. IV. Fill-in the Blanks 1. Coal reserves are typically categorized by _____ and _________. 2. Although _________ has the most coal reserves in the world, it is ________ which produces (and consumes) the most coal. 3. Tar sands are grains of sands containing a viscous carbonaceous substance called ____________. 4. The combustible fuel in the oil shale is a waxy solid called ____________. 5. The substance remaining in the bottom of the distillation column is _________. 6. The propane and butane removed from natural gas are usually liquefied under pressure and sold as _________________. 7. Natural gas is the cleanest form of fossil fuel because it has the highest _________ ratio. 8. The other name for liquefied petroleum gas is the __________ gas. 9. The United States reached its peak oil production sometime during _________. 10. The total amount of a resource produced as of today is called _____________ production. V. PROJECT I - Hubbert’s Curve Describe the major assumptions implicit in King Hubert’s prediction concerning oil production. Use his estimates on the world petroleum production (shown on the cover of this book) to calculate the growth rate during decades spanning from 1900 to the present. 1. Plot the cumulative total production as a function of time. What does this graph look like? Why? 2. What is the size of total endowment? 3. What is the doubling time at around the turn of the century? 4. Based on his prediction, and assume the pattern of production follows his estimates, how much longer, do our petroleum resources last? PROJECT II – Status of Energy Resources In this project you are asked to investigate the status of energy resources, reserves, and use in the United States and compare it with those of the world as a whole. The main source of data is the Energy Information Agency of the US Department of Energy (http://eia.doe.gov), but other sources may need to be considered. Please answer the following questions: 1. What is the total annual energy consumption (in quads and billions of barrels of “oil equivalent”) for various energy sources: oil, gas, coal, renewable, and nuclear? for various energy sectors: transportation, industrialized, residential and commercial? 2. What fraction of the primary energy consumption is used to generate electricity? Give the percentage from each source. 3. What are the ultimate sizes of the US and the world reserves? 4. What is the energy consumption per capita? How fast does total energy consumption increase with a rise in the gross domestic product (GDP)? 5. What is the energy consumption per every $1,000 of income? Compare US data with China, India, and the European Union. 171 Work Sheet For Project II The United States Quads Percent 1. Consumption a. Consumption by Source Oil Gas Coal Nuclear Renewable b. Consumption by Sector Transportation Industrial Residential & Commercial 2. Electricity by Source Oil Gas Coal Nuclear Renewable 3. Ultimate Size of Reserves 4. Energy Consumption Per Capita a. Annual Rate of Energy Growth b. Annual Rate of Growth in GDP X X X X X X X X The World Quads Percent 172